Unabalanced 10 with Ace side count

There is a game where I may have to use unbalanced 10 (unusual insurance rules).

I was thinking of adding an Ace side count - have not used one before, would be glad for any pointers as to how to use it...

Do I simply look at EOR for an A, multiply by extra aces per deck to get % adv ? Is there an intelligent way to combine this with the UB10 ?

Thanks

D.